<!doctype html>
<html>
<head>
<meta charset='UTF-8'><meta name='viewport' content='width=device-width initial-scale=1'>
<title>java07</title><link href='https://fonts.loli.net/css?family=PT+Serif:400,400italic,700,700italic&subset=latin,cyrillic-ext,cyrillic,latin-ext' rel='stylesheet' type='text/css' /><style type='text/css'>html {overflow-x: initial !important;}:root { --bg-color:#ffffff; --text-color:#333333; --select-text-bg-color:#B5D6FC; --select-text-font-color:auto; --monospace:"Lucida Console",Consolas,"Courier",monospace; }
html { font-size: 14px; background-color: var(--bg-color); color: var(--text-color); font-family: "Helvetica Neue", Helvetica, Arial, sans-serif; -webkit-font-smoothing: antialiased; }
body { margin: 0px; padding: 0px; height: auto; bottom: 0px; top: 0px; left: 0px; right: 0px; font-size: 1rem; line-height: 1.42857; overflow-x: hidden; background: inherit; }
iframe { margin: auto; }
a.url { word-break: break-all; }
a:active, a:hover { outline: 0px; }
.in-text-selection, ::selection { text-shadow: none; background: var(--select-text-bg-color); color: var(--select-text-font-color); }
#write { margin: 0px auto; height: auto; width: inherit; word-break: normal; word-wrap: break-word; position: relative; white-space: normal; overflow-x: visible; padding-top: 40px; }
#write.first-line-indent p { text-indent: 2em; }
#write.first-line-indent li p, #write.first-line-indent p * { text-indent: 0px; }
#write.first-line-indent li { margin-left: 2em; }
.for-image #write { padding-left: 8px; padding-right: 8px; }
body.typora-export { padding-left: 30px; padding-right: 30px; }
.typora-export .footnote-line, .typora-export li, .typora-export p { white-space: pre-wrap; }
@media screen and (max-width: 500px) {
  body.typora-export { padding-left: 0px; padding-right: 0px; }
  #write { padding-left: 20px; padding-right: 20px; }
  .CodeMirror-sizer { margin-left: 0px !important; }
  .CodeMirror-gutters { display: none !important; }
}
#write li > figure:first-child { margin-top: -20px; }
#write ol, #write ul { position: relative; }
img { max-width: 100%; vertical-align: middle; }
button, input, select, textarea { color: inherit; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; }
input[type="checkbox"], input[type="radio"] { line-height: normal; padding: 0px; }
*, ::after, ::before { box-sizing: border-box; }
#write h1, #write h2, #write h3, #write h4, #write h5, #write h6, #write p, #write pre { width: inherit; }
#write h1, #write h2, #write h3, #write h4, #write h5, #write h6, #write p { position: relative; }
h1, h2, h3, h4, h5, h6 { break-after: avoid-page; break-inside: avoid; orphans: 2; }
p { orphans: 4; }
h1 { font-size: 2rem; }
h2 { font-size: 1.8rem; }
h3 { font-size: 1.6rem; }
h4 { font-size: 1.4rem; }
h5 { font-size: 1.2rem; }
h6 { font-size: 1rem; }
.md-math-block, .md-rawblock, h1, h2, h3, h4, h5, h6, p { margin-top: 1rem; margin-bottom: 1rem; }
.hidden { display: none; }
.md-blockmeta { color: rgb(204, 204, 204); font-weight: 700; font-style: italic; }
a { cursor: pointer; }
sup.md-footnote { padding: 2px 4px; background-color: rgba(238, 238, 238, 0.7); color: rgb(85, 85, 85); border-radius: 4px; cursor: pointer; }
sup.md-footnote a, sup.md-footnote a:hover { color: inherit; text-transform: inherit; text-decoration: inherit; }
#write input[type="checkbox"] { cursor: pointer; width: inherit; height: inherit; }
figure { overflow-x: auto; margin: 1.2em 0px; max-width: calc(100% + 16px); padding: 0px; }
figure > table { margin: 0px !important; }
tr { break-inside: avoid; break-after: auto; }
thead { display: table-header-group; }
table { border-collapse: collapse; border-spacing: 0px; width: 100%; overflow: auto; break-inside: auto; text-align: left; }
table.md-table td { min-width: 32px; }
.CodeMirror-gutters { border-right: 0px; background-color: inherit; }
.CodeMirror-linenumber { user-select: none; }
.CodeMirror { text-align: left; }
.CodeMirror-placeholder { opacity: 0.3; }
.CodeMirror pre { padding: 0px 4px; }
.CodeMirror-lines { padding: 0px; }
div.hr:focus { cursor: none; }
#write pre { white-space: pre-wrap; }
#write.fences-no-line-wrapping pre { white-space: pre; }
#write pre.ty-contain-cm { white-space: normal; }
.CodeMirror-gutters { margin-right: 4px; }
.md-fences { font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; overflow: visible; white-space: pre; background: inherit; position: relative !important; }
.md-diagram-panel { width: 100%; margin-top: 10px; text-align: center; padding-top: 0px; padding-bottom: 8px; overflow-x: auto; }
#write .md-fences.mock-cm { white-space: pre-wrap; }
.md-fences.md-fences-with-lineno { padding-left: 0px; }
#write.fences-no-line-wrapping .md-fences.mock-cm { white-space: pre; overflow-x: auto; }
.md-fences.mock-cm.md-fences-with-lineno { padding-left: 8px; }
.CodeMirror-line, twitterwidget { break-inside: avoid; }
.footnotes { opacity: 0.8; font-size: 0.9rem; margin-top: 1em; margin-bottom: 1em; }
.footnotes + .footnotes { margin-top: 0px; }
.md-reset { margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: top; background: 0px 0px; text-decoration: none; text-shadow: none; float: none; position: static; width: auto; height: auto; white-space: nowrap; cursor: inherit; -webkit-tap-highlight-color: transparent; line-height: normal; font-weight: 400; text-align: left; box-sizing: content-box; direction: ltr; }
li div { padding-top: 0px; }
blockquote { margin: 1rem 0px; }
li .mathjax-block, li p { margin: 0.5rem 0px; }
li { margin: 0px; position: relative; }
blockquote > :last-child { margin-bottom: 0px; }
blockquote > :first-child, li > :first-child { margin-top: 0px; }
.footnotes-area { color: rgb(136, 136, 136); margin-top: 0.714rem; padding-bottom: 0.143rem; white-space: normal; }
#write .footnote-line { white-space: pre-wrap; }
@media print {
  body, html { border: 1px solid transparent; height: 99%; break-after: avoid; break-before: avoid; }
  #write { margin-top: 0px; padding-top: 0px; border-color: transparent !important; }
  .typora-export * { -webkit-print-color-adjust: exact; }
  html.blink-to-pdf { font-size: 13px; }
  .typora-export #write { padding-left: 32px; padding-right: 32px; padding-bottom: 0px; break-after: avoid; }
  .typora-export #write::after { height: 0px; }
  @page { margin: 20mm 0px; }
}
.footnote-line { margin-top: 0.714em; font-size: 0.7em; }
a img, img a { cursor: pointer; }
pre.md-meta-block { font-size: 0.8rem; min-height: 0.8rem; white-space: pre-wrap; background: rgb(204, 204, 204); display: block; overflow-x: hidden; }
p > .md-image:only-child:not(.md-img-error) img, p > img:only-child { display: block; margin: auto; }
p > .md-image:only-child { display: inline-block; width: 100%; }
#write .MathJax_Display { margin: 0.8em 0px 0px; }
.md-math-block { width: 100%; }
.md-math-block:not(:empty)::after { display: none; }
[contenteditable="true"]:active, [contenteditable="true"]:focus { outline: 0px; box-shadow: none; }
.md-task-list-item { position: relative; list-style-type: none; }
.task-list-item.md-task-list-item { padding-left: 0px; }
.md-task-list-item > input { position: absolute; top: 0px; left: 0px; margin-left: -1.2em; margin-top: calc(1em - 10px); border: none; }
.math { font-size: 1rem; }
.md-toc { min-height: 3.58rem; position: relative; font-size: 0.9rem; border-radius: 10px; }
.md-toc-content { position: relative; margin-left: 0px; }
.md-toc-content::after, .md-toc::after { display: none; }
.md-toc-item { display: block; color: rgb(65, 131, 196); }
.md-toc-item a { text-decoration: none; }
.md-toc-inner:hover { text-decoration: underline; }
.md-toc-inner { display: inline-block; cursor: pointer; }
.md-toc-h1 .md-toc-inner { margin-left: 0px; font-weight: 700; }
.md-toc-h2 .md-toc-inner { margin-left: 2em; }
.md-toc-h3 .md-toc-inner { margin-left: 4em; }
.md-toc-h4 .md-toc-inner { margin-left: 6em; }
.md-toc-h5 .md-toc-inner { margin-left: 8em; }
.md-toc-h6 .md-toc-inner { margin-left: 10em; }
@media screen and (max-width: 48em) {
  .md-toc-h3 .md-toc-inner { margin-left: 3.5em; }
  .md-toc-h4 .md-toc-inner { margin-left: 5em; }
  .md-toc-h5 .md-toc-inner { margin-left: 6.5em; }
  .md-toc-h6 .md-toc-inner { margin-left: 8em; }
}
a.md-toc-inner { font-size: inherit; font-style: inherit; font-weight: inherit; line-height: inherit; }
.footnote-line a:not(.reversefootnote) { color: inherit; }
.md-attr { display: none; }
.md-fn-count::after { content: "."; }
code, pre, samp, tt { font-family: var(--monospace); }
kbd { margin: 0px 0.1em; padding: 0.1em 0.6em; font-size: 0.8em; color: rgb(36, 39, 41); background: rgb(255, 255, 255); border: 1px solid rgb(173, 179, 185); border-radius: 3px; box-shadow: rgba(12, 13, 14, 0.2) 0px 1px 0px, rgb(255, 255, 255) 0px 0px 0px 2px inset; white-space: nowrap; vertical-align: middle; }
.md-comment { color: rgb(162, 127, 3); opacity: 0.8; font-family: var(--monospace); }
code { text-align: left; vertical-align: initial; }
a.md-print-anchor { white-space: pre !important; border-width: initial !important; border-style: none !important; border-color: initial !important; display: inline-block !important; position: absolute !important; width: 1px !important; right: 0px !important; outline: 0px !important; background: 0px 0px !important; text-decoration: initial !important; text-shadow: initial !important; }
.md-inline-math .MathJax_SVG .noError { display: none !important; }
.html-for-mac .inline-math-svg .MathJax_SVG { vertical-align: 0.2px; }
.md-math-block .MathJax_SVG_Display { text-align: center; margin: 0px; position: relative; text-indent: 0px; max-width: none; max-height: none; min-height: 0px; min-width: 100%; width: auto; overflow-y: hidden; display: block !important; }
.MathJax_SVG_Display, .md-inline-math .MathJax_SVG_Display { width: auto; margin: inherit; display: inline-block !important; }
.MathJax_SVG .MJX-monospace { font-family: var(--monospace); }
.MathJax_SVG .MJX-sans-serif { font-family: sans-serif; }
.MathJax_SVG { display: inline; font-style: normal; font-weight: 400; line-height: normal; zoom: 90%; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; }
.MathJax_SVG * { transition: none; }
.MathJax_SVG_Display svg { vertical-align: middle !important; margin-bottom: 0px !important; }
.os-windows.monocolor-emoji .md-emoji { font-family: "Segoe UI Symbol", sans-serif; }
.md-diagram-panel > svg { max-width: 100%; }
[lang="mermaid"] svg, [lang="flow"] svg { max-width: 100%; }
[lang="mermaid"] .node text { font-size: 1rem; }
table tr th { border-bottom: 0px; }
video { max-width: 100%; display: block; margin: 0px auto; }
iframe { max-width: 100%; width: 100%; border: none; }
.highlight td, .highlight tr { border: 0px; }


.CodeMirror { height: auto; }
.CodeMirror.cm-s-inner { background: inherit; }
.CodeMirror-scroll { overflow-y: hidden; overflow-x: auto; z-index: 3; }
.CodeMirror-gutter-filler, .CodeMirror-scrollbar-filler { background-color: rgb(255, 255, 255); }
.CodeMirror-gutters { border-right: 1px solid rgb(221, 221, 221); background: inherit; white-space: nowrap; }
.CodeMirror-linenumber { padding: 0px 3px 0px 5px; text-align: right; color: rgb(153, 153, 153); }
.cm-s-inner .cm-keyword { color: rgb(119, 0, 136); }
.cm-s-inner .cm-atom, .cm-s-inner.cm-atom { color: rgb(34, 17, 153); }
.cm-s-inner .cm-number { color: rgb(17, 102, 68); }
.cm-s-inner .cm-def { color: rgb(0, 0, 255); }
.cm-s-inner .cm-variable { color: rgb(0, 0, 0); }
.cm-s-inner .cm-variable-2 { color: rgb(0, 85, 170); }
.cm-s-inner .cm-variable-3 { color: rgb(0, 136, 85); }
.cm-s-inner .cm-string { color: rgb(170, 17, 17); }
.cm-s-inner .cm-property { color: rgb(0, 0, 0); }
.cm-s-inner .cm-operator { color: rgb(152, 26, 26); }
.cm-s-inner .cm-comment, .cm-s-inner.cm-comment { color: rgb(170, 85, 0); }
.cm-s-inner .cm-string-2 { color: rgb(255, 85, 0); }
.cm-s-inner .cm-meta { color: rgb(85, 85, 85); }
.cm-s-inner .cm-qualifier { color: rgb(85, 85, 85); }
.cm-s-inner .cm-builtin { color: rgb(51, 0, 170); }
.cm-s-inner .cm-bracket { color: rgb(153, 153, 119); }
.cm-s-inner .cm-tag { color: rgb(17, 119, 0); }
.cm-s-inner .cm-attribute { color: rgb(0, 0, 204); }
.cm-s-inner .cm-header, .cm-s-inner.cm-header { color: rgb(0, 0, 255); }
.cm-s-inner .cm-quote, .cm-s-inner.cm-quote { color: rgb(0, 153, 0); }
.cm-s-inner .cm-hr, .cm-s-inner.cm-hr { color: rgb(153, 153, 153); }
.cm-s-inner .cm-link, .cm-s-inner.cm-link { color: rgb(0, 0, 204); }
.cm-negative { color: rgb(221, 68, 68); }
.cm-positive { color: rgb(34, 153, 34); }
.cm-header, .cm-strong { font-weight: 700; }
.cm-del { text-decoration: line-through; }
.cm-em { font-style: italic; }
.cm-link { text-decoration: underline; }
.cm-error { color: red; }
.cm-invalidchar { color: red; }
.cm-constant { color: rgb(38, 139, 210); }
.cm-defined { color: rgb(181, 137, 0); }
div.CodeMirror span.CodeMirror-matchingbracket { color: rgb(0, 255, 0); }
div.CodeMirror span.CodeMirror-nonmatchingbracket { color: rgb(255, 34, 34); }
.cm-s-inner .CodeMirror-activeline-background { background: inherit; }
.CodeMirror { position: relative; overflow: hidden; }
.CodeMirror-scroll { height: 100%; outline: 0px; position: relative; box-sizing: content-box; background: inherit; }
.CodeMirror-sizer { position: relative; }
.CodeMirror-gutter-filler, .CodeMirror-hscrollbar, .CodeMirror-scrollbar-filler, .CodeMirror-vscrollbar { position: absolute; z-index: 6; display: none; }
.CodeMirror-vscrollbar { right: 0px; top: 0px; overflow: hidden; }
.CodeMirror-hscrollbar { bottom: 0px; left: 0px; overflow: hidden; }
.CodeMirror-scrollbar-filler { right: 0px; bottom: 0px; }
.CodeMirror-gutter-filler { left: 0px; bottom: 0px; }
.CodeMirror-gutters { position: absolute; left: 0px; top: 0px; padding-bottom: 30px; z-index: 3; }
.CodeMirror-gutter { white-space: normal; height: 100%; box-sizing: content-box; padding-bottom: 30px; margin-bottom: -32px; display: inline-block; }
.CodeMirror-gutter-wrapper { position: absolute; z-index: 4; background: 0px 0px !important; border: none !important; }
.CodeMirror-gutter-background { position: absolute; top: 0px; bottom: 0px; z-index: 4; }
.CodeMirror-gutter-elt { position: absolute; cursor: default; z-index: 4; }
.CodeMirror-lines { cursor: text; }
.CodeMirror pre { border-radius: 0px; border-width: 0px; background: 0px 0px; font-family: inherit; font-size: inherit; margin: 0px; white-space: pre; word-wrap: normal; color: inherit; z-index: 2; position: relative; overflow: visible; }
.CodeMirror-wrap pre { word-wrap: break-word; white-space: pre-wrap; word-break: normal; }
.CodeMirror-code pre { border-right: 30px solid transparent; width: fit-content; }
.CodeMirror-wrap .CodeMirror-code pre { border-right: none; width: auto; }
.CodeMirror-linebackground { position: absolute; left: 0px; right: 0px; top: 0px; bottom: 0px; z-index: 0; }
.CodeMirror-linewidget { position: relative; z-index: 2; overflow: auto; }
.CodeMirror-wrap .CodeMirror-scroll { overflow-x: hidden; }
.CodeMirror-measure { position: absolute; width: 100%; height: 0px; overflow: hidden; visibility: hidden; }
.CodeMirror-measure pre { position: static; }
.CodeMirror div.CodeMirror-cursor { position: absolute; visibility: hidden; border-right: none; width: 0px; }
.CodeMirror div.CodeMirror-cursor { visibility: hidden; }
.CodeMirror-focused div.CodeMirror-cursor { visibility: inherit; }
.cm-searching { background: rgba(255, 255, 0, 0.4); }
@media print {
  .CodeMirror div.CodeMirror-cursor { visibility: hidden; }
}


:root { --active-file-bg-color: rgba(32, 43, 51, 0.63); --active-file-text-color: white; --bg-color: #f3f2ee; --text-color: #1f0909; --control-text-color: #444; --rawblock-edit-panel-bd: #e5e5e5; --select-text-bg-color: rgba(32, 43, 51, 0.63); --select-text-font-color: white; }
pre { --select-text-bg-color: #36284e; --select-text-font-color: #fff; }
html { font-size: 16px; }
html, body { background-color: rgb(243, 242, 238); font-family: "PT Serif", "Times New Roman", Times, serif; color: rgb(31, 9, 9); line-height: 1.5em; }
#write { max-width: 40em; }
ol li { list-style-type: decimal; list-style-position: outside; }
ul li { list-style-type: disc; list-style-position: outside; }
ol, ul { list-style: none; }
blockquote, q { quotes: none; }
blockquote::before, blockquote::after, q::before, q::after { content: none; }
table { border-collapse: collapse; border-spacing: 0px; }
h1, h2, h3, h4, h5, h6 { font-weight: bold; }
h1 { font-size: 1.875em; line-height: 1.6em; margin-top: 2em; }
h2, h3 { font-size: 1.3125em; line-height: 1.15; margin-top: 2.28571em; margin-bottom: 1.15em; }
h3 { font-weight: normal; }
h4 { font-size: 1.125em; margin-top: 2.67em; }
h5, h6 { font-size: 1em; }
h1 { border-bottom: 1px solid; margin-bottom: 1.875em; padding-bottom: 0.8125em; }
a { text-decoration: none; color: rgb(6, 85, 136); }
a:hover, a:active { text-decoration: underline; }
p, blockquote, .md-fences { margin-bottom: 1.5em; }
h1, h2, h3, h4, h5, h6 { margin-bottom: 1.5em; }
blockquote { font-style: italic; border-left: 5px solid; margin-left: 2em; padding-left: 1em; }
ul, ol { margin: 0px 0px 1.5em 1.5em; }
.md-meta, .md-before, .md-after { color: rgb(153, 153, 153); }
table { margin-bottom: 1.5em; font-size: 1em; }
thead th, tfoot th { padding: 0.25em 0.25em 0.25em 0.4em; text-transform: uppercase; }
th { text-align: left; }
td { vertical-align: top; padding: 0.25em 0.25em 0.25em 0.4em; }
code, .md-fences { background-color: rgb(218, 218, 218); }
code { padding-left: 2px; padding-right: 2px; }
.md-fences { margin-left: 2em; margin-bottom: 3em; padding-left: 1ch; padding-right: 1ch; }
pre, code, tt { font-size: 0.875em; line-height: 1.71429em; }
h1 { line-height: 1.3em; font-weight: normal; margin-bottom: 0.5em; }
p + ul, p + ol { margin-top: 0.5em; }
h3 + ul, h4 + ul, h5 + ul, h6 + ul, h3 + ol, h4 + ol, h5 + ol, h6 + ol { margin-top: 0.5em; }
li > ul, li > ol { margin-top: inherit; margin-bottom: 0px; }
li ol > li { list-style-type: lower-alpha; }
li li ol > li { list-style-type: lower-roman; }
h2, h3 { margin-bottom: 0.75em; }
hr { border-top: none; border-right: none; border-bottom: 1px solid; border-left: none; }
h1 { border-color: rgb(197, 197, 197); }
blockquote { border-color: rgb(186, 186, 186); color: rgb(101, 101, 101); }
blockquote ul, blockquote ol { margin-left: 0px; }
.ty-table-edit { background-color: transparent; }
thead { background-color: rgb(218, 218, 218); }
tr:nth-child(2n) { background: rgb(232, 231, 231); }
hr { border-color: rgb(197, 197, 197); }
.task-list { padding-left: 1rem; }
.md-task-list-item { padding-left: 1.5rem; list-style-type: none; }
.md-task-list-item > input::before { content: "√"; display: inline-block; width: 1.25rem; height: 1.6rem; vertical-align: middle; text-align: center; color: rgb(221, 221, 221); background-color: rgb(243, 242, 238); }
.md-task-list-item > input:checked::before, .md-task-list-item > input[checked]::before { color: inherit; }
#write pre.md-meta-block { min-height: 1.875rem; color: rgb(85, 85, 85); border: 0px; background: transparent; margin-left: 1em; margin-top: 1em; }
.md-image > .md-meta { color: rgb(155, 81, 70); }
.md-image > .md-meta { font-family: Menlo, "Ubuntu Mono", Consolas, "Courier New", "Microsoft Yahei", "Hiragino Sans GB", "WenQuanYi Micro Hei", serif; }
#write > h3.md-focus::before { left: -1.5rem; color: rgb(153, 153, 153); border-color: rgb(153, 153, 153); }
#write > h4.md-focus::before { left: -1.5rem; top: 0.25rem; color: rgb(153, 153, 153); border-color: rgb(153, 153, 153); }
#write > h5.md-focus::before { left: -1.5rem; color: rgb(153, 153, 153); border-color: rgb(153, 153, 153); }
#write > h6.md-focus::before { left: -1.5rem; top: 0.3125rem; color: rgb(153, 153, 153); border-color: rgb(153, 153, 153); }
.md-toc:focus .md-toc-content { margin-top: 19px; }
.md-toc-content:empty::before { color: rgb(6, 85, 136); }
.md-toc-item { color: rgb(6, 85, 136); }
#write div.md-toc-tooltip { background-color: rgb(243, 242, 238); }
#typora-sidebar { background-color: rgb(243, 242, 238); box-shadow: rgba(0, 0, 0, 0.376) 0px 6px 12px; }
.pin-outline #typora-sidebar { background: inherit; box-shadow: none; border-right: 1px dashed; }
.pin-outline #typora-sidebar:hover .outline-title-wrapper { border-left: 1px dashed; }
.outline-item:hover { background-color: rgb(218, 218, 218); border-left: 28px solid rgb(218, 218, 218); border-right: 18px solid rgb(218, 218, 218); }
.typora-node .outline-item:hover { border-right: 28px solid rgb(218, 218, 218); }
.outline-expander::before { content: ""; font-family: FontAwesome; font-size: 14px; top: 1px; }
.outline-expander:hover::before, .outline-item-open > .outline-item > .outline-expander::before { content: ""; }
.modal-content { background-color: rgb(243, 242, 238); }
.auto-suggest-container ul li { list-style-type: none; }
.megamenu-menu, #top-titlebar, #top-titlebar *, .megamenu-content { background: rgb(243, 242, 238); color: rgb(31, 9, 9); }
.megamenu-menu-header { border-bottom: 1px dashed rgb(32, 43, 51); }
.megamenu-menu { box-shadow: none; border-right: 1px dashed; }
header, .context-menu, .megamenu-content, footer { font-family: "PT Serif", "Times New Roman", Times, serif; color: rgb(31, 9, 9); }
#megamenu-back-btn { color: rgb(31, 9, 9); border-color: rgb(31, 9, 9); }
.megamenu-menu-header #megamenu-menu-header-title::before { color: rgb(31, 9, 9); }
.megamenu-menu-list li a:hover, .megamenu-menu-list li a.active { color: inherit; background-color: rgb(232, 231, 223); }
.long-btn:hover { background-color: rgb(232, 231, 223); }
#recent-file-panel tbody tr:nth-child(2n-1) { background-color: transparent !important; }
.megamenu-menu-panel tbody tr:hover td:nth-child(2) { color: inherit; }
.megamenu-menu-panel .btn { background-color: rgb(210, 209, 209); }
.btn-default { background-color: transparent; }
.typora-sourceview-on #toggle-sourceview-btn, .ty-show-word-count #footer-word-count { background: rgb(199, 197, 197); }
#typora-quick-open { background-color: inherit; }
.md-diagram-panel { margin-top: 8px; }
.file-list-item-file-name { font-weight: initial; }
.file-list-item-summary { opacity: 1; }
.file-list-item { color: rgb(119, 119, 119); }
.file-list-item.active { background-color: inherit; color: black; }
.ty-side-sort-btn.active { background-color: inherit; }
.file-list-item.active .file-list-item-file-name { font-weight: bold; }
.file-list-item { opacity: 1 !important; }
.file-library-node.active > .file-node-background { background-color: var(--active-file-bg-color); }
.file-tree-node.active > .file-node-content { color: var(--active-file-text-color); }
.md-task-list-item > input { margin-left: -1.6em; margin-top: calc(1rem - 12px); }
input { border: 1px solid rgb(170, 170, 170); }
.megamenu-menu-header #megamenu-menu-header-title, .megamenu-menu-header:hover, .megamenu-menu-header:focus { color: inherit; }
.dropdown-menu .divider { border-color: rgb(229, 229, 229); }
.os-windows-7 strong, .os-windows-7 strong { font-weight: 760; }





 .typora-export li, .typora-export p, .typora-export,  .footnote-line {white-space: normal;} 
</style>
</head>
<body class='typora-export os-windows' >
<div  id='write'  class = 'is-node'><div class='md-toc' mdtype='toc'><p class="md-toc-content"><span class="md-toc-item md-toc-h2" data-ref="n2"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n2">1:成员变量和局部变量的区别(理解)</a></span><span class="md-toc-item md-toc-h4" data-ref="n3"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n3">(1)在类中的位置不同</a></span><span class="md-toc-item md-toc-h4" data-ref="n5"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n5">(2)在内存中的位置不同</a></span><span class="md-toc-item md-toc-h4" data-ref="n7"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n7">(3)生命周期不同</a></span><span class="md-toc-item md-toc-h4" data-ref="n9"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n9">(4)初始化值不同</a></span><span class="md-toc-item md-toc-h2" data-ref="n11"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n11">2:类作为形式参数的问题?(理解)</a></span><span class="md-toc-item md-toc-h2" data-ref="n13"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n13">3:匿名对象(理解)</a></span><span class="md-toc-item md-toc-h2" data-ref="n24"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n24">4:封装(理解)</a></span><span class="md-toc-item md-toc-h4" data-ref="n25"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n25">(1)隐藏实现细节，提供公共的访问方式</a></span><span class="md-toc-item md-toc-h4" data-ref="n26"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n26">(2)好处：</a></span><span class="md-toc-item md-toc-h4" data-ref="n33"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n33">(3)设计原则</a></span><span class="md-toc-item md-toc-h4" data-ref="n36"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n36">(4)private是封装的一种体现。</a></span><span class="md-toc-item md-toc-h2" data-ref="n38"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n38">5:private关键字(掌握)</a></span><span class="md-toc-item md-toc-h2" data-ref="n46"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n46">6:this关键字(掌握)</a></span><span class="md-toc-item md-toc-h4" data-ref="n47"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n47">(1)代表当前类的引用对象</a></span><span class="md-toc-item md-toc-h4" data-ref="n49"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n49">(2)this的应用场景：</a></span><span class="md-toc-item md-toc-h2" data-ref="n55"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n55">7:构造方法(掌握)</a></span><span class="md-toc-item md-toc-h4" data-ref="n56"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n56">(1)作用：用于对对象的数据进行初始化</a></span><span class="md-toc-item md-toc-h4" data-ref="n57"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n57">(2)格式：</a></span><span class="md-toc-item md-toc-h6" data-ref="n60"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n60">A:方法名和类名相同</a></span><span class="md-toc-item md-toc-h6" data-ref="n62"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n62">B:没有返回值类型，连void都不能有</a></span><span class="md-toc-item md-toc-h6" data-ref="n64"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n64">C:没有返回值</a></span><span class="md-toc-item md-toc-h4" data-ref="n66"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n66">(3)构造方法的注意事项</a></span><span class="md-toc-item md-toc-h6" data-ref="n70"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n70">A:如果我们没写构造方法，系统将提供一个默认的无参构造方法</a></span><span class="md-toc-item md-toc-h6" data-ref="n73"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n73">B:如果我们给出了构造方法，系统将不再提供默认构造方法</a></span><span class="md-toc-item md-toc-h4" data-ref="n72"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n72">(4)给成员变量赋值的方式</a></span><span class="md-toc-item md-toc-h6" data-ref="n74"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n74">A:setXxx()</a></span><span class="md-toc-item md-toc-h6" data-ref="n127"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n127">B:带参构造方法</a></span><span class="md-toc-item md-toc-h4" data-ref="n75"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n75">(5)标准案例</a></span><span class="md-toc-item md-toc-h2" data-ref="n79"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n79">8:代码：Student s = new Student();做了哪些事情?(理解)</a></span><span class="md-toc-item md-toc-h2" data-ref="n95"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n95">9:面向对象的练习题(掌握)</a></span><span class="md-toc-item md-toc-h2" data-ref="n97"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n97">10:static关键字(理解)</a></span><span class="md-toc-item md-toc-h4" data-ref="n98"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n98">(1)静态的意思。可以修饰成员变量和成员方法。</a></span><span class="md-toc-item md-toc-h4" data-ref="n99"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n99">(2)静态的特点：</a></span><span class="md-toc-item md-toc-h6" data-ref="n100"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n100">A:随着类的加载而加载</a></span><span class="md-toc-item md-toc-h6" data-ref="n101"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n101">B:优先与对象存在</a></span><span class="md-toc-item md-toc-h6" data-ref="n102"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n102">C:被类的所有对象共享</a></span><span class="md-toc-item md-toc-h6" data-ref="n104"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n104">D:可以通过类名调用</a></span><span class="md-toc-item md-toc-h4" data-ref="n106"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n106">(3)静态的内存图</a></span><span class="md-toc-item md-toc-h4" data-ref="n108"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n108">(4)静态的注意事项；</a></span><span class="md-toc-item md-toc-h6" data-ref="n109"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n109">A:在静态方法中没有this对象</a></span><span class="md-toc-item md-toc-h6" data-ref="n110"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n110">B:静态只能访问静态(代码测试过)</a></span><span class="md-toc-item md-toc-h4" data-ref="n111"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n111">(5)静态变量和成员变量的区别</a></span><span class="md-toc-item md-toc-h6" data-ref="n112"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n112">A:所属不同</a></span><span class="md-toc-item md-toc-h6" data-ref="n114"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n114">B:内存位置不同</a></span><span class="md-toc-item md-toc-h6" data-ref="n116"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n116">C:生命周期不同</a></span><span class="md-toc-item md-toc-h6" data-ref="n118"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n118">D:调用不同</a></span><span class="md-toc-item md-toc-h4" data-ref="n120"><a class="md-toc-inner" style="cursor: pointer;" href="#header-n120">(6)main方法是静态的</a></span></p></div><h2><a name='header-n2' class='md-header-anchor '></a>1:成员变量和局部变量的区别(理解)</h2><h4><a name='header-n3' class='md-header-anchor '></a>(1)在类中的位置不同</h4><p>成员变量：类中方法外
局部变量：方法定义中或者方法声明上</p><h4><a name='header-n5' class='md-header-anchor '></a>(2)在内存中的位置不同</h4><p>成员变量：在堆中
局部变量：在栈中</p><h4><a name='header-n7' class='md-header-anchor '></a>(3)生命周期不同</h4><p>成员变量：随着对象的创建而存在，随着对象的消失而消失
局部变量：随着方法的调用而存在，随着方法的调用完毕而消失</p><h4><a name='header-n9' class='md-header-anchor '></a>(4)初始化值不同</h4><p>成员变量：有默认值
局部变量：没有默认值，必须定义，赋值，然后才能使用
<span>		</span></p><h2><a name='header-n11' class='md-header-anchor '></a>2:类作为形式参数的问题?(理解)</h2><p>(1)如果你看到一个方法需要的参数是一个类名，就应该知道这里实际需要的是一个具体的对象。</p><h2><a name='header-n13' class='md-header-anchor '></a>3:匿名对象(理解)</h2><ul><li><p>(1)没有名字的对象</p></li><li><p>(2)应用场景</p><ul><li>A:调用方法，仅仅只调用一次的时候。</li><li>b:可以作为实际参数传递。</li></ul></li></ul><h2><a name='header-n24' class='md-header-anchor '></a>4:封装(理解)</h2><h4><a name='header-n25' class='md-header-anchor '></a>(1)隐藏实现细节，提供公共的访问方式</h4><h4><a name='header-n26' class='md-header-anchor '></a>(2)好处：</h4><ul><li>A:隐藏实现细节，提供公共的访问方式</li><li>B:提高代码的复用性</li><li>C:提高代码的安全性</li></ul><h4><a name='header-n33' class='md-header-anchor '></a>(3)设计原则</h4><p>把不想让外界知道的实现细节给隐藏起来，提供公共的访问方式</p><h4><a name='header-n36' class='md-header-anchor '></a>(4)private是封装的一种体现。</h4><p>封装：类，方法，private修饰成员变量</p><h2><a name='header-n38' class='md-header-anchor '></a>5:private关键字(掌握)</h2><ul><li>(1)私有的意义，可以修饰成员变量和成员方法</li><li>(2)特点：被private修饰的后的成员只能在本类中被访问</li><li>(3)private的应用：
以后再写一个类的时候：
把所有的成员变量给private了
提供对应的getXxx()/setXxx()方法</li></ul><h2><a name='header-n46' class='md-header-anchor '></a>6:this关键字(掌握)</h2><h4><a name='header-n47' class='md-header-anchor '></a>(1)代表当前类的引用对象</h4><p>记住：哪个对象调用方法，该方法内部的this就代表那个对象</p><h4><a name='header-n49' class='md-header-anchor '></a>(2)this的应用场景：</h4><ul><li>A:解决了局部变量隐藏成员变量的问题</li><li>B:其实this还有其他的应用，明天讲解。</li></ul><h2><a name='header-n55' class='md-header-anchor '></a>7:构造方法(掌握)</h2><h4><a name='header-n56' class='md-header-anchor '></a>(1)作用：用于对对象的数据进行初始化</h4><h4><a name='header-n57' class='md-header-anchor '></a>(2)格式：</h4><h6><a name='header-n60' class='md-header-anchor '></a>A:方法名和类名相同</h6><h6><a name='header-n62' class='md-header-anchor '></a>B:没有返回值类型，连void都不能有</h6><h6><a name='header-n64' class='md-header-anchor '></a>C:没有返回值</h6><p><span>	</span></p><blockquote><p>思考题：构造方法中可不可以有return语句呢?
可以。而是我们写成这个样子就OK了：return;
其实，在任何的void类型的方法的最后你都可以写上：return;</p></blockquote><h4><a name='header-n66' class='md-header-anchor '></a>(3)构造方法的注意事项</h4><h6><a name='header-n70' class='md-header-anchor '></a>A:如果我们没写构造方法，系统将提供一个默认的无参构造方法</h6><h6><a name='header-n73' class='md-header-anchor '></a>B:如果我们给出了构造方法，系统将不再提供默认构造方法</h6><p><span>	</span>如果这个时候，我们要使用无参构造方法，就必须自己给出。
<span>	</span><strong>推荐：永远手动自己给出无参构造方法。</strong></p><h4><a name='header-n72' class='md-header-anchor '></a>(4)给成员变量赋值的方式</h4><h6><a name='header-n74' class='md-header-anchor '></a>A:setXxx()</h6><h6><a name='header-n127' class='md-header-anchor '></a>B:带参构造方法</h6><h4><a name='header-n75' class='md-header-anchor '></a>(5)标准案例</h4><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="java" style="break-inside: unset;"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="java"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 4px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation" style=""><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">class</span> <span class="cm-def">Student</span> {</span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-keyword">private</span> <span class="cm-variable-3">String</span> <span class="cm-variable">name</span>;</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-keyword">private</span> <span class="cm-variable-3">int</span> <span class="cm-variable">age</span>;</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-keyword">public</span> <span class="cm-variable">Student</span>(){}</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-keyword">public</span> <span class="cm-variable">Student</span>(<span class="cm-variable-3">String</span> <span class="cm-variable">name</span>,<span class="cm-variable-3">int</span> <span class="cm-variable">age</span>) {</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;<span class="cm-keyword">this</span>.<span class="cm-variable">name</span> <span class="cm-operator">=</span> <span class="cm-variable">name</span>;</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;<span class="cm-keyword">this</span>.<span class="cm-variable">age</span> <span class="cm-operator">=</span> <span class="cm-variable">age</span>;</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp;  }</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-keyword">public</span> <span class="cm-variable-3">String</span> <span class="cm-variable">getName</span>() {</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;<span class="cm-keyword">return</span> <span class="cm-variable">name</span>;</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp;  }</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-keyword">public</span> <span class="cm-variable-3">void</span> <span class="cm-variable">setName</span>(<span class="cm-variable-3">String</span> <span class="cm-variable">name</span>) {</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;<span class="cm-keyword">this</span>.<span class="cm-variable">name</span> <span class="cm-operator">=</span> <span class="cm-variable">name</span>;</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp;  }</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-keyword">public</span> <span class="cm-variable-3">int</span> <span class="cm-variable">getAge</span>() {</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;<span class="cm-keyword">return</span> <span class="cm-variable">age</span>;</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp;  }</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-keyword">public</span> <span class="cm-variable-3">void</span> <span class="cm-variable">setAge</span>(<span class="cm-variable-3">int</span> <span class="cm-variable">age</span>) {</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;<span class="cm-keyword">this</span>.<span class="cm-variable">age</span> <span class="cm-operator">=</span> <span class="cm-variable">age</span>;</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp;  }</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;">}</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom: 0px solid transparent; top: 648px;"></div><div class="CodeMirror-gutters" style="display: none; height: 648px;"></div></div></div></pre><p> 测试：</p><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="java"><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang="java"><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 4px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation" style=""><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-keyword">class</span> <span class="cm-def">StudentDemo</span> {</span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp;<span class="cm-keyword">public</span> <span class="cm-keyword">static</span> <span class="cm-variable-3">void</span> <span class="cm-variable">main</span>(<span class="cm-variable-3">String</span>[] <span class="cm-variable">args</span>) {</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;<span class="cm-comment">//方式1</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;<span class="cm-variable">Student</span> <span class="cm-variable">s1</span> <span class="cm-operator">=</span> <span class="cm-keyword">new</span> <span class="cm-variable">Student</span>();</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;<span class="cm-variable">s1</span>.<span class="cm-variable">setName</span>(<span class="cm-string">"林青霞"</span>);</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;<span class="cm-variable">s1</span>.<span class="cm-variable">setAge</span>(<span class="cm-number">27</span>);</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;<span class="cm-variable">System</span>.<span class="cm-variable">out</span>.<span class="cm-variable">println</span>(<span class="cm-variable">s1</span>.<span class="cm-variable">getName</span>()<span class="cm-operator">+</span><span class="cm-string">"---"</span><span class="cm-operator">+</span><span class="cm-variable">s1</span>.<span class="cm-variable">getAge</span>());</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;<span class="cm-comment">//方式2</span></span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;<span class="cm-variable">Student</span> <span class="cm-variable">s2</span> <span class="cm-operator">=</span> <span class="cm-keyword">new</span> <span class="cm-variable">Student</span>(<span class="cm-string">"刘意"</span>,<span class="cm-number">30</span>);</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp; &nbsp; &nbsp; &nbsp;<span class="cm-variable">System</span>.<span class="cm-variable">out</span>.<span class="cm-variable">println</span>(<span class="cm-variable">s2</span>.<span class="cm-variable">getName</span>()<span class="cm-operator">+</span><span class="cm-string">"---"</span><span class="cm-operator">+</span><span class="cm-variable">s2</span>.<span class="cm-variable">getAge</span>());</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"> &nbsp;  }</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;">}</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom: 0px solid transparent; top: 312px;"></div><div class="CodeMirror-gutters" style="display: none; height: 312px;"></div></div></div></pre><h2><a name='header-n79' class='md-header-anchor '></a>8:代码：Student s = new Student();做了哪些事情?(理解)</h2><ol start='' ><li>把Student.class文件加载到内存     </li><li>在栈内存为s开辟空间  </li><li>在堆内存为学生对象申请空间</li><li>给学生的成员变量进行默认初始化。null,0</li><li>给学生的成员变量进行显示初始化。林青霞,27</li><li>通过构造方法给成员变量进行初始化。刘意,30</li><li>对象构造完毕，把地址赋值给s变量
<span>	</span></li></ol><h2><a name='header-n95' class='md-header-anchor '></a>9:面向对象的练习题(掌握)</h2><pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang=""><div class="CodeMirror cm-s-inner CodeMirror-wrap" lang=""><div style="overflow: hidden; position: relative; width: 3px; height: 0px; top: 0px; left: 4px;"><textarea autocorrect="off" autocapitalize="off" spellcheck="false" tabindex="0" style="position: absolute; bottom: -1em; padding: 0px; width: 1000px; height: 1em; outline: none;"></textarea></div><div class="CodeMirror-scrollbar-filler" cm-not-content="true"></div><div class="CodeMirror-gutter-filler" cm-not-content="true"></div><div class="CodeMirror-scroll" tabindex="-1"><div class="CodeMirror-sizer" style="margin-left: 0px; margin-bottom: 0px; border-right-width: 0px; padding-right: 0px; padding-bottom: 0px;"><div style="position: relative; top: 0px;"><div class="CodeMirror-lines" role="presentation"><div role="presentation" style="position: relative; outline: none;"><div class="CodeMirror-measure"><pre><span>xxxxxxxxxx</span></pre></div><div class="CodeMirror-measure"></div><div style="position: relative; z-index: 1;"></div><div class="CodeMirror-code" role="presentation" style=""><div class="CodeMirror-activeline" style="position: relative;"><div class="CodeMirror-activeline-background CodeMirror-linebackground"></div><div class="CodeMirror-gutter-background CodeMirror-activeline-gutter" style="left: 0px; width: 0px;"></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;">(1)标准的手机类的定义和测试</span></pre></div><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;">(2)Demo类有求和方法，Test类进行测试。</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-tab" role="presentation" cm-text="	">    </span>什么时候定义成员变量?</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;"><span class="cm-tab" role="presentation" cm-text="	">    </span>当该变量是用来描述一个类的时候。</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;">(3)长方形案例</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;">(4)员工案例</span></pre><pre class=" CodeMirror-line " role="presentation"><span role="presentation" style="padding-right: 0.1px;">(5)MyMath案例(自己提供加减乘除并测试)</span></pre></div></div></div></div></div><div style="position: absolute; height: 0px; width: 1px; border-bottom: 0px solid transparent; top: 168px;"></div><div class="CodeMirror-gutters" style="display: none; height: 168px;"></div></div></div></pre><h2><a name='header-n97' class='md-header-anchor '></a>10:static关键字(理解)</h2><h4><a name='header-n98' class='md-header-anchor '></a>(1)静态的意思。可以修饰成员变量和成员方法。</h4><h4><a name='header-n99' class='md-header-anchor '></a>(2)静态的特点：</h4><h6><a name='header-n100' class='md-header-anchor '></a>A:随着类的加载而加载</h6><h6><a name='header-n101' class='md-header-anchor '></a>B:优先与对象存在</h6><h6><a name='header-n102' class='md-header-anchor '></a>C:被类的所有对象共享</h6><p>这其实也是我们判断该不该使用静态的依据。
举例：饮水机和水杯的问题思考</p><h6><a name='header-n104' class='md-header-anchor '></a>D:可以通过类名调用</h6><p>既可以通过对象名调用，也可以通过类名调用，建议通过类名调用。</p><h4><a name='header-n106' class='md-header-anchor '></a>(3)静态的内存图</h4><p>静态的内容在方法区的静态区</p><h4><a name='header-n108' class='md-header-anchor '></a>(4)静态的注意事项；</h4><h6><a name='header-n109' class='md-header-anchor '></a>A:在静态方法中没有this对象</h6><h6><a name='header-n110' class='md-header-anchor '></a>B:静态只能访问静态(代码测试过)</h6><h4><a name='header-n111' class='md-header-anchor '></a>(5)静态变量和成员变量的区别</h4><h6><a name='header-n112' class='md-header-anchor '></a>A:所属不同</h6><p>静态变量：属于类，类变量
成员变量：属于对象，对象变量，实例变量</p><h6><a name='header-n114' class='md-header-anchor '></a>B:内存位置不同</h6><p>静态变量：方法区的静态区
成员变量：堆内存</p><h6><a name='header-n116' class='md-header-anchor '></a>C:生命周期不同</h6><p>静态变量：静态变量是随着类的加载而加载，随着类的消失而消失
成员变量：成员变量是随着对象的创建而存在，随着对象的消失而消失</p><h6><a name='header-n118' class='md-header-anchor '></a>D:调用不同</h6><p>静态变量：可以通过对象名调用，也可以通过类名调用
成员变量：只能通过对象名调用</p><h4><a name='header-n120' class='md-header-anchor '></a>(6)main方法是静态的</h4><p><code>public</code>:权限最大
<code>static</code>:不用创建对象调用
<code>void</code>:返回值给jvm没有意义
<code>main</code>:就是一个常见的名称。
<code>String[] args</code>:可以接收数据，提供程序的灵活性
    格式：<code>java MainDemo hello world java</code>
            <code>java MainDemo 10 20 30</code></p></div>
</body>
</html>